Today, monocrystalline silicon is the most widely used semiconductor material for producing semiconductor devices and integrated circuits. One method for producing a silicon single crystal is to grow a crystal from molten silicon according to the Czochralski (CZ) method. By virtue of the specific growth process, such silicon (which will be referred to as CZ silicon in the following) is supersaturated with oxygen. That is, the silicon includes interstitial oxygen in a typical concentration of higher than 5E17 cm−3.
Thermal treatment cycles which are typically employed in the fabrication of electronic devices can cause the precipitation of oxygen in silicon wafers which are supersaturated in oxygen. Depending upon their location in the wafer, oxygen precipitates can be harmful or beneficial. Oxygen precipitates, which may include oxygen agglomerates and oxygen-vacancy agglomerates, may induce the formation of defects, such as dislocations or stacking faults. These defects, in turn, may degrade the performance of semiconductor devices if these defects occur in the active areas of the devices. However, oxygen precipitates located distant to the active area (in the bulk of the wafer) are capable of trapping undesired metal impurities that may come into contact with the wafer in the fabrication of electronic devices. The use of oxygen precipitates located in the bulk of the wafer to trap metals is commonly referred to as internal or intrinsic gettering.
It is desirable to produce a silicon wafer having a zone or region near the surface of the wafer which is free of oxygen precipitates (commonly referred to as a “denuded zone” or a “precipitate free zone”), and a gettering zone adjoining the denuded zone. It is further desirable to precisely control the thickness of the denuded zone in this process.